Papers by Author: S. Dmitriev

Abstract: Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol radiofrequency plasma after pre-activation its surface in an oxygen plasma were studied. The influence of plasma treatment conditions on basic membrane characteristics, i.e. pore size and shape, wettability, and water permeability, was studied. It has been shown that the plasma treatment of membrane can significantly improve its performance characteristics.

Abstract: This paper describes a structure and electrotransport properties of poly(ethylene terephthalate) track membrane (PET TM) modified by plasma of thiophene. It is shown that the deposition of the polymer on the track membrane surface by plasma polymerization of thiophene in case of forming a semipermeable layer results in creation of composite nanomembrane having in electrolyte solutions of asymmetry of conductivity - a rectification effect. It is caused by presence in the membrane of two layers with various functional groups, and also by changing of the pore geometry. Such type membranes can be used for creation of chemical and biochemical sensors.

Abstract: The eddy current transformer (EST) of the transformer type is used to construct a sensor for investigating titanium sheets joined by a welded joint. The article provides the key technical information about the eddy current transformer used and describes the methodology of measurements that makes it possible to control defects in the welding seams of titanium alloys. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. The designed measuring system eliminates the main drawback of eddy current transformers (the small area of the electromagnetic field), simultaneously significantly reducing the noise level due to the use of high-quality amplifiers and filters, and searches for defects in and alloys of different metals. A measurement procedure that allows one to perform high-accuracy monitoring of flaws in different alloys is described. Experiments were conducted on welded BT1-0 titanium plates. The article contains the results of these measurements. The dependence data facilitates the assessment of the quality of welding seams and helps make an educated conclusion about welding quality.

Abstract: We applied eddy current transducer (ECT) to examine the electric steel parameters. The research topic is considered relevant due to the need for evaluation and forecasting of safe operating life of electric steel products. A scheme that uses a computer as a generator and receiver of signals from windings is proposed. Having the designed transducer as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. The article provides the key technical information about the eddy current transformer used and describes the methodology of measurements that makes it possible to control steel to dielectric transition. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. The curve of introduced voltage amplitude as a function of sensor location was constructed to study in details the introduced voltage drop at the ferromagnetic-dielectric interface. Presentation of induced voltage changes in the form of mathematical dependences enables to elicit the ways of interaction between electromagnetic field of eddy-current converter and residual magnetic field of steel.